Szalai A J, Dick T A
Department of Zoology, University of Manitoba, Winnipeg, Canada.
J Parasitol. 1991 Dec;77(6):914-22.
Twenty species of fishes (n = 20,759) were collected from Dauphin Lake, Manitoba, Canada, to determine the types and numbers of ectoparasites they harbored. Counts of ectoparasites on fishes collected with different gear were compared to evaluate different methods of collection and to estimate rates of recruitment of ectoparasites by fishes. Ectoparasites were found on 11 species of fishes and the majority of these were parasitic leeches (Myzobdella moorei, Cystobranchus verilli, and Placobdella montifera) and parasitic Crustacea (Argulus appendiculosus and Lernaea cyprinacea). Some fishes also were infested by neascus-type metacercariae (blackspot) or had tumors (lymphocystis). The prevalence of ectoparasites was correlated with the abundance, feeding habits, and spatial distribution of fish species. Argulus appendiculosus and blackspot were more prevalent on benthic fishes, whereas M. moorei and tumors were more prevalent on limnetic fishes. Mark-recapture records showed that fishes occupying shallow (less than or equal to 1.5 m) water had a higher prevalence of infestation and 28 of 29 infected fishes caught by gill nets were captured in shallow water. Placobdella montifera was the only ectoparasite found on fishes from deep (1.5-3.5 m) water and the only species that was acquired by fishes previously released with no ectoparasite (2 of 239 fishes). The littoral zone (less than or equal to 1.5 m) comprises only 14% of the surface area and 3% of the volume of Dauphin Lake, yet 72% of all gill-netted fishes harboring ectoparasites were collected there. Intensities of ectoparasites estimated from gill net and pound net samples were similar, but prevalence of ectoparasites estimated from samples obtained with gill nets was lower.
从加拿大曼尼托巴省多芬湖采集了20种鱼类（n = 20759），以确定它们所携带的体外寄生虫的种类和数量。比较了用不同渔具采集的鱼类身上的体外寄生虫数量，以评估不同的采集方法，并估计鱼类体外寄生虫的补充率。在11种鱼类身上发现了体外寄生虫，其中大多数是寄生水蛭（穆氏蛭、维氏囊蛭和蒙氏扁蛭）和寄生甲壳类动物（附肢鱼虱和鲤锚头鳋）。一些鱼类还受到新囊蚴型尾蚴（黑点病）感染或患有肿瘤（淋巴囊肿）。体外寄生虫的患病率与鱼类的丰度、摄食习性和空间分布相关。附肢鱼虱和黑点病在底栖鱼类中更为普遍，而穆氏蛭和肿瘤在沿岸鱼类中更为普遍。标记重捕记录显示，栖息在浅水（小于或等于1.5米）区域的鱼类感染率更高，用刺网捕获的29条受感染鱼类中有28条是在浅水区捕获的。蒙氏扁蛭是在深水（1.5 - 3.5米）区域鱼类身上发现的唯一体外寄生虫，也是唯一在先前未携带体外寄生虫而放流的鱼类身上出现的物种（239条鱼中有2条）。沿岸带（小于或等于1.5米）仅占多芬湖表面积的14%和体积的3%，然而，所有携带体外寄生虫的刺网捕获鱼类中有72%是在那里采集到的。根据刺网和围网样本估计的体外寄生虫强度相似，但根据刺网样本估计的体外寄生虫患病率较低。
